FROMLIST: [PATCH v6 05/12] arm: vdso: Add support for CLOCK_MONOTONIC_RAW

(cherry pick from url https://patchwork.kernel.org/patch/10052099/)

Take an effort to recode the arm64 vdso code from assembler to C
previously submitted by Andrew Pinski <apinski@cavium.com>, rework
it for use in both arm and arm64, overlapping any optimizations
for each architecture. But instead of landing it in arm64, land the
result into lib/vdso and unify both implementations to simplify
future maintenance.

Add a case for CLOCK_MONOTONIC_RAW to match up with support that
is available in arm64's vdso.

Signed-off-by: Mark Salyzyn <salyzyn@android.com>
Cc: James Morse <james.morse@arm.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Dmitry Safonov <dsafonov@virtuozzo.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Laura Abbott <labbott@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Andy Gross <andy.gross@linaro.org>
Cc: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Andrew Pinski <apinski@cavium.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Bug: 63737556
Bug: 20045882
Change-Id: If9c09d131e236ba4a483dbc122e6b876f471df72

arch/arm/include/asm/vdso_datapage.h

@@ -34,6 +34,11 @@ typedef u32 vdso_wtm_clock_nsec_t;
 typedef u32 vdso_xtime_clock_sec_t;
 #endif
 
+#ifndef _VDSO_RAW_TIME_SEC_T
+#define _VDSO_RAW_TIME_SEC_T
+typedef u32 vdso_raw_time_sec_t;
+#endif
+
 /* Try to be cache-friendly on systems that don't implement the
  * generic timer: fit the unconditionally updated fields in the first
  * 32 bytes.
@@ -58,6 +63,12 @@ struct vdso_data {
 	u64 xtime_clock_snsec;	/* CLOCK_REALTIME sub-ns base */
 	u32 tz_minuteswest;	/* timezone info for gettimeofday(2) */
 	u32 tz_dsttime;
+
+	/* Raw clocksource multipler */
+	u32 cs_raw_mult;
+	/* Raw time */
+	vdso_raw_time_sec_t raw_time_sec;
+	u32 raw_time_nsec;
 };
 
 union vdso_data_store {

arch/arm/kernel/vdso.c

@@ -319,9 +319,12 @@ void update_vsyscall(struct timekeeper *tk)
 
 	if (!vdso_data->use_syscall) {
 		vdso_data->cs_cycle_last	= tk->tkr_mono.cycle_last;
+		vdso_data->raw_time_sec		= tk->raw_sec;
+		vdso_data->raw_time_nsec	= tk->tkr_raw.xtime_nsec;
 		vdso_data->xtime_clock_sec	= tk->xtime_sec;
 		vdso_data->xtime_clock_snsec	= tk->tkr_mono.xtime_nsec;
 		vdso_data->cs_mono_mult		= tk->tkr_mono.mult;
+		vdso_data->cs_raw_mult		= tk->tkr_raw.mult;
 		/* tkr_mono.shift == tkr_raw.shift */
 		vdso_data->cs_shift		= tk->tkr_mono.shift;
 		vdso_data->cs_mask		= tk->tkr_mono.mask;

arch/arm/vdso/vgettimeofday.c

@@ -194,6 +194,40 @@ static notrace int do_monotonic(const struct vdso_data *vd, struct timespec *ts)
 	return 0;
 }
 
+static notrace int do_monotonic_raw(const struct vdso_data *vd,
+				    struct timespec *ts)
+{
+	u32 seq, mult, shift;
+	u64 nsec, cycle_last;
+	u64 mask;
+	vdso_raw_time_sec_t sec;
+
+	do {
+		seq = vdso_read_begin(vd);
+
+		if (vd->use_syscall)
+			return -1;
+
+		cycle_last = vd->cs_cycle_last;
+
+		mult = vd->cs_raw_mult;
+		shift = vd->cs_shift;
+		mask = vd->cs_mask;
+
+		sec = vd->raw_time_sec;
+		nsec = vd->raw_time_nsec;
+
+	} while (unlikely(vdso_read_retry(vd, seq)));
+
+	nsec += get_clock_shifted_nsec(cycle_last, mult, mask);
+	nsec >>= shift;
+	/* open coding timespec_add_ns to save a ts->tv_nsec = 0 */
+	ts->tv_sec = sec + __iter_div_u64_rem(nsec, NSEC_PER_SEC, &nsec);
+	ts->tv_nsec = nsec;
+
+	return 0;
+}
+
 #else /* CONFIG_ARM_ARCH_TIMER */
 
 static notrace int do_realtime(const struct vdso_data *vd, struct timespec *ts)
@@ -206,6 +240,12 @@ static notrace int do_monotonic(const struct vdso_data *vd, struct timespec *ts)
 	return -1;
 }
 
+static notrace int do_monotonic_raw(const struct vdso_data *vd,
+				    struct timespec *ts)
+{
+	return -1;
+}
+
 #endif /* CONFIG_ARM_ARCH_TIMER */
 
 notrace int __vdso_clock_gettime(clockid_t clock, struct timespec *ts)
@@ -227,6 +267,10 @@ notrace int __vdso_clock_gettime(clockid_t clock, struct timespec *ts)
 		if (do_monotonic(vd, ts))
 			goto fallback;
 		break;
+	case CLOCK_MONOTONIC_RAW:
+		if (do_monotonic_raw(vd, ts))
+			goto fallback;
+		break;
 	default:
 		goto fallback;
 	}